Thermal marking systems and methods of control

ABSTRACT

A target marking system includes a light source emitting a thermal beam and an optics assembly directing the thermal beam to impact a target, the target directing radiation to the optics assembly in response to the impact. The target marking system further includes a detector, and an optics assembly optically connected to the detector.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation-in-part of U.S. patentapplication Ser. No. 13/271,924, filed Oct. 12, 2011, which claims thebenefit of U.S. Provisional Application No. 61/392,697, filed Oct. 13,2010. The entire disclosures of each of these applications areincorporated herein by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

REFERENCE TO A “SEQUENCE LISTING”

Not applicable.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present disclosure relates to systems and methods for marking atarget, and in particular, to systems and methods for marking a targetwith thermal radiation.

2. Description of Related Art

In combat arenas, some target marking applications may require use ofradiation, such as a thermal beam, to mark targets in a way that may notbe detectable by the target. For example, since thermal beams are notvisible with the naked eye or with common infrared viewers, a soldier orother user of a thermal target marking system may be able to identifyand/or otherwise mark a potential target without the target being ableto see, for example, a targeting dot on his person. However, use ofthermal radiation to mark targets is not without its own inherentcomplications.

A quantum cascade laser (“QCL”) may be utilized to emit thermal beams insuch applications, however, because the beams emitted by QCLs areinherently divergent, employing a QCL in such applications typicallyrequires additional componentry configured to shape the thermal beam.For example, known beam shaping techniques may be used to increase theresolution of the thermal beam, thereby allowing the beam to appearsmaller when impinging upon the target. However, such shaping techniquestypically reduce the intensity of the thermal beam. Thus, the resultingbeam, although desirably narrower, may be difficult for thermal beamdetectors to view at great distances. As a result, such marking systemsmay be undesirable for use by, for example, snipers or other medium tolong-range combat applications.

In addition, QCLs are inherently inefficient as light sources. Forexample, most typical QCLs give off a great deal of heat relative to theamount of light produced when the QCL is provided with an electricalcurrent or voltage. While this inherent inefficiency may not be terriblyproblematic in a laboratory or other environment in which power andcooling components can be adapted relatively easily for use with suchQCLs, such inefficiencies make it much more difficult to utilize QCLsin, for example, hand-held target marking devices or other devices inwhich space, weight, mobility, and/or other parameters are much moretightly constrained.

For example, utilizing a QCL in a hand-held target marker typicallyrequires the use of one or more portable power sources such as, forexample, batteries or the like. Because such batteries are generally lowenergy power sources, and because such batteries may only be capable ofproviding power for a limited time, utilizing such batteries to power arelatively inefficient QCL can be problematic. For example, suchbatteries may be depleted relatively quickly due to the large power drawplaced on them by the QCL. In addition, even when powered by suchbatteries, the QCL may give off substantial amounts of heat and mayrequire one or more cooling components to be thermally connected theretoto optimize QCL performance. Such cooling components may represent anadditional parasitic load on the batteries being utilized, and mayfurther reduce the useful life of such batteries. Due to thesedifficulties, the use of QCLs in hand-held or other portable targetmarking devices has been limited.

The embodiments of the present disclosure are aimed at overcoming one ormore of these deficiencies.

SUMMARY OF THE INVENTION

In an exemplary embodiment of the present disclosure, a target markingsystem includes a plurality of light sources, each light source of theplurality of light sources configured to generate a respective beam ofthermal radiation, and an optics assembly configured to form an emittedbeam from the respective beams and to direct the emitted beam toward thetarget.

In another exemplary embodiment of the present disclosure, a targetmarking system includes a light source generating a beam of thermalradiation and a cooling element thermally connected to the light source.

In a further exemplary embodiment of the present disclosure, a targetmarking system includes a plurality of light sources, each light sourceof the plurality of light sources configured to generate a respectivebeam of thermal radiation, and an optics assembly configured to form anemitted beam from the respective beams and to direct the emitted beamtoward the target. The optics assembly includes a plurality ofadjustment windows, each adjustment window of the plurality ofadjustment windows enabling manual alignment of at least one of therespective beams of thermal radiation. For example, the adjustmentwindows may be moved in unison.

In a further exemplary embodiment of the present disclosure, a method ofcontrolling a target marking system includes scanning a target with adetector tuned to detect thermal radiation, the detector comprising apixel array and scanning sequentially along individual rows of thearray, identifying an area of the target likely to be impinged upon byan emitted beam of the target marking system, and energizing a lightsource during a time period in which the detector scans along a row ofthe array corresponding to the identified area. The method also includesde-energizing the light source during a remaining time period in whichthe detector scans along one or more rows of the array not correspondingto the identified area.

In still another exemplary embodiment of the present disclosure, amethod of controlling a target marking system, includes directing powerto a quantum cascade laser with one of a buck converter, a flybackconverter, a forward converter, a buck-boost converter, a single endedprimary inductor converter, a two switch forward converter, a push-pullconverter, a half bridge converter, and a full bridge converter. Themethod also includes generating a beam of thermal radiation with thequantum cascade laser in response to the power received.

In a further exemplary embodiment, a target marking system includes alight source configured to emit a beam of radiation, and a controllerconnected to the light source and configured to pulse the beam emittedby the light source. The controller includes a drive circuit comprisinga first converter connected in series with a second converter, and acapacitor connected in series between the first and second converters.The target marking system also includes a power source connected to thelight source via the drive circuit.

In another exemplary embodiment, a target marking system includes alight source configured to emit a beam of thermal radiation, an opticsassembly receiving the beam and directing the beam to exit a housing ofthe target marking system, and a controller disposed within the housingand connected to the light source. The controller includes a drivecircuit having a first converter connected in series with a secondconverter, and a capacitor connected in series between the first andsecond converters. The system also includes a power source connected tothe light source via the drive circuit. The drive circuit provides asubstantially constant current to the light source during pulsedoperation of the light source.

In still another exemplary embodiment of the present disclosure, amethod of controlling a target marking system includes directing asubstantially constant current from a power source of the target markingsystem to a light source of the system via a drive circuit. The drivecircuit includes a first converter connected in series with a secondconverter, and a capacitor connected in series between the first andsecond converters. The method also includes generating a pulsed beam ofradiation with the light source in response to receipt of thesubstantially constant current.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of a target marking system accordingto an exemplary embodiment of the present disclosure.

FIG. 2 is a partial schematic of a portion of an exemplary targetmarking system.

FIG. 3 is a partial schematic of a portion of another exemplary targetmarking system of the present disclosure.

FIG. 4 is a partial schematic of a portion of still another exemplarytarget marking system of the present disclosure.

FIG. 5 is a partial schematic of a portion of yet another exemplarytarget marking system of the present disclosure.

FIG. 6 is a partial schematic of a portion of a further exemplary targetmarking system of the present disclosure.

FIG. 7 illustrates a light source thermally connected to a coolingelement according to an exemplary embodiment of the present disclosure.

FIG. 8 illustrates a light source thermally connected to a coolingelement according to another exemplary embodiment of the presentdisclosure.

FIG. 9 illustrates a light source thermally connected to a coolingelement according to a further exemplary embodiment of the presentdisclosure.

FIG. 10 is a partial schematic of a portion of an exemplary targetmarking system of the present disclosure.

FIG. 11 illustrates an exemplary light source output graph and anexemplary detector according to an embodiment of the present disclosure.

FIG. 12 is a schematic illustration of a target marking system accordingto another exemplary embodiment of the present disclosure.

FIG. 13 illustrates an exemplary drive circuit for use with a targetmarking system of the present disclosure.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a target marking system 10 according to an exemplaryembodiment of the present disclosure. As shown in FIG. 1, an exemplarysystem 10 may include, among other things, an optics assembly 12, adetector 14, and at least one light source 16. While exemplaryembodiments of the system 10 may include a single light source 16,additional exemplary embodiments of the system 10 may include at leastone additional light source 18. The detector 14 and the light sources16, 18 may be optically, electrically, physically and/or otherwiseconnected to the optics assembly 12 in any known way. For example, theoptical connection between the detector 14 and the optics assembly 12may enable light and/or other forms of radiation to pass between theoptics assembly 12 and the detector 14 along a beam path 30. Inaddition, the optical connection between the optics assembly 12 and theone or more light sources 16, 18 may enable light and/or other forms ofradiation to pass between the optics assembly 12 and the light sources16, 18 along respective beam paths 32, 34.

The target marking system 10 may further include, for example, acontroller 20, a cooling element 22, and/or a power source 38. Thecontroller 20 may be configured to control each of the components of thesystem 10, and the controller 20 may be electrically, and/or otherwisecontrollably connected to, for example, the detector 14, light sources16, 18, cooling element 22, and/or power source 38 to facilitate suchcontrol. As will be described in greater detail below, the coolingelement 22 may be thermally connected to at least one of the lightsources 16, 18, and the power source 38 may be configured to providepower to the light sources 16, 18, controller 20, cooling element 22,detector 14, and/or other components of the target marking system 10. Asshown in FIG. 1, the power source 38 may be electrically connected toone or more components of the target marking system 10 via thecontroller 20. In such an exemplary embodiment, the controller 20 mayassist in distributing power from the power source 38 to the componentsof the system 10. Alternatively, one or more components of the system 10may be directly connected to the power source 38.

The target marking system 10 may be configured for use in conjunctionwith and/or for removable connection to one or more handheld devicessuch as, for example, a firearm 36. Although not illustrated in FIG. 1,it is understood that the system 10 may further include one or morelocking assemblies, clamping mechanisms, and/or other componentsconfigured to assist in removably attaching the system 10 to the firearm36. Such locking assemblies or clamping mechanisms may enable the userto mount and/or otherwise connect the system 10 to any one of aplurality of commercially available mounts based on user preference. Inan exemplary embodiment, the system 10 may be mounted on a Picatiny railof the firearm 36. An additional exemplary embodiments, however, thesystem 10 may be connected to other known rails, such as, but notlimited to dove tail rails and T-rails. In addition, the lockingassembly and/or clamping mechanism may enable the system 10 to be easilyremovably attachable to other portions of the firearm 36 based on userpreference or other ergonomic considerations.

The target marking system 10 may include a housing 11, and at least oneof the first and second light sources 16, 18 may be disposedsubstantially within the housing 11. The housing 11 may define one ormore orifices through which beams, pulses, signals, or other likeradiation emitted from the light sources 16, 18 may exit the housing 11.In still another exemplary embodiment, the light sources 16, 18, opticsassembly 12, and/or the detector 14 may be disposed substantially withinthe housing 11. In a further exemplary embodiment, each component of thesystem 10 may be disposed substantially within the housing 11 and, insuch an exemplary embodiment, the system 10 may be a single-piece systemremovably connectable to the firearm 36.

As shown in FIG. 12, in a further exemplary embodiment, a target markingsystem 100 may comprise at least two housings containing the componentsof the system 100. Wherever possible, like components of the systems 10,100 are described herein using like item numbers. The exemplary system100 may have a first housing 11 containing at least a portion of a firstoptics assembly 12, the light sources 16, 18, the controller 20, thecooling element 22, and the power source 38. The exemplary system 100may also comprise a second housing 11 a containing at least a portion ofa second optics assembly 12 a, a second controller 20 a, and a secondpower source 38 a. The second housing 11 a may further include, forexample, the detector 14 and the display 60 described herein. It isunderstood that, in an exemplary embodiment, the second housing 11 a,second optics assembly 12 a, second controller 20 a, and second powersource 38 a may be substantially optically, structurally, functionally,and/or operably similar to the respective housing 11, optics assembly12, controller 20, and power source 38 described herein. In addition,although one or more elements of the above components may be disposed inseparate housings 11, 11 a, it is understood that together, theseseparate elements may comprise a single component of the system 100. Forexample, although the first optics assembly 12 may be disposed withinthe first housing 11 and the second optics assembly 12 a may be disposedwithin the second housing 11 a, in an exemplary embodiment, the firstand second optics assemblies 12, 12 a may comprise a single opticsassembly of the system 100. Likewise, although the first controller 20may be disposed within the first housing 11 and the second controller 20a may be disposed within the second housing 11 a, in an exemplaryembodiment, the first and second controllers 20, 20 a may comprise asingle controller of the system 100.

As shown schematically in FIG. 12, the first and second housings 11, 11a may be removably attachable to the firearm 36 using any of the lockingassemblies, clamping mechanisms, rails, and/or other componentsdescribed herein. In addition, the first and second controllers 20, 20 amay be electrically and/or operably connected via any connection 66known in the art. Such a connection 66 may be made by wire, Bluetooth,RF, and/or other known connection means. Accordingly, information, data,signals, and/or control commands may be transmitted between thecontrollers 20, 20 a, via the connection 66, to facilitate operation ofone or more components of the system 100.

It is understood that any of the components, control strategies, circuittopographies, operations, functions, and/or other characteristics of thevarious embodiments described herein may be employed by either or bothof the exemplary systems 10, 100 illustrated in FIGS. 1 and 12. However,for ease of description, the exemplary embodiment of the system 10illustrated in FIG. 1 shall be described for the remainder of thisdisclosure unless otherwise specified. Light beams, pulses, signals, orother like radiation emitted from the light sources 16, 18 may exit thehousing 11 and/or otherwise pass from the target marking system 10 alongone or more respective emitted beam paths 76. Such emitted radiation 24may impinge upon a target 26 and, depending upon the configuration ofthe target 26, such contact may result in the emission of radiation 28from the target 26. This contact may also result in radiation 74 beingrejected and/or otherwise reflected by the target 26, as well asradiation 70 being scattered by the target 26. Such re-emitted,reflected, and/or scattered radiation 28, 74, 70 may enter the housing11 and/or the target marking system 10.

In an exemplary embodiment, the target 26 may direct such radiation 28,74, 70 to pass through the same optics assembly 12 used to condition theradiation emitted by the light sources 16, 18. In such an embodiment,the radiation 28, 74, 70 may pass from the optics assembly 12 to thedetector 14 along the beam path 30. In this way, the target markingsystem 10 may utilize a single optics assembly 12 to condition thebeams, pulses, signals, or other radiation 24 emitted from the lightsources 16, 18, to condition re-emitted, reflected, and/or scatteredradiation 28, 74, 70 directed to the optics assembly 12 by the target26, and to direct such radiation 28, 74, 70 to the detector 14. Sincethe same optics assembly 12 is employed by the light sources 16, 18 andthe detector 14, the target marking system 10 of the present disclosuremay be significantly smaller, lighter, less complicated, less expensive,and easier to calibrate than marking systems utilizing discrete opticsassemblies for the light sources and the detector associated therewith.However, as shown in FIG. 12, in additional exemplary embodiments, atarget marking system 100 may employ a second optics assembly 12 a tocondition such radiation 28, 74, 70.

Referring again to FIG. 1, the light sources 16, 18 may comprise, forexample, any of a variety of lasers. Typically, the light sources 16, 18are self-contained, and one or more of the light sources 16, 18 mayinclude one or more dedicated lenses separate from the optics assembly12. The light sources 16, 18, may comprise, for example, any combinationof a green laser, a red laser, a QCL, a super continuum laser, aninfrared laser, an infrared light emitting diode (“LED”), a white andcolored LED, a laser having an output of approximately 5 mW (it isunderstood that lasers having an output greater than approximately 5 mWor less than approximately 5 mW may also be used), an interband cascadelaser (“ICL”), and a short wavelength infrared laser (“SWIR”). It isunderstood that a SWIR may emit a signal, beam, pulse, and/or otherradiation having a wavelength of between, approximately 0.9 μm andapproximately 2.5 μm. It is also understood that a QCL may be selectedto operate in substantially ambient temperature conditions whileproducing a beam, pulse, signal, and/or other radiation having awavelength between approximately 2 μm and approximately 30 μm. Forexample, a QCL may emit a beam having a wavelength between approximately2 μm and approximately 5 μm (mid-wave) or between approximately 8 μm andapproximately 30 μm (long-wave). In a further exemplary embodiment, thelight sources 16, 18 may each comprise QCLs, thereby providing for atarget marking system 10 configured to produce and/or otherwise emitbeams having a plurality of different useful wavelengths for markingand/or other known applications. For example, the system 10 may comprisea fusion imager or other such device configured to emit and/or detectradiation in more than one spectral band and/or having more than onewavelength. Such fusion imagers may be useful in, for example, boththermal marking and night vision applications. In still anotherexemplary embodiment, one or more of the light sources 16, 18 maycomprise a carbon dioxide laser.

As shown in FIG. 1, any of the light sources 16, 18 employed by thetarget marking system 10 may be operably connected to an appropriatecontroller. The controller 20 may include an appropriate driver, controlcircuitry signal processor, transformers, inductors, capacitors, and/orany other control, boost, and/or drive components. Such a driver may be,for example, configured to assist in controllably operating the lightsources 16, 18. In addition, such a signal processor may be configuredto modify the gain, contrast, brightness, color, and/or other opticalcharacteristics of an input signal received from the detector 14. Suchan input signal may be representative of a change in resistivity and/orother thermal, mechanical, optical, or electrical characteristic of oneor more components of the detector 14, and such components may be pixelsthereof. Thus, the controller 20 may be configured to receive an inputsignal from the detector 14 and produce a digitally enhanced outputsignal in response to the input signal. The controller 20 may send theoutput signal to, for example, a liquid crystal display, an organiclight emitting diode, or any other like display 60. Alternatively, inadditional exemplary embodiments, the detector 14 may be configured toproduce such a digitally enhanced output signal, and direct such asignal to the controller 20 and/or the display 60.

The controller 20 and its components may be configured to operate atleast one of the light sources 16, 18 in either pulsed or continuousmodes of operation. Such components may include, one or more pulsegenerators, encoders, amplifiers, pulse switchers, and/or other knowncontroller components. The controller 20 may control the light sources16, 18 to emit radiation at any of the desirable wavelengths describedherein. In addition, the controller 20 may control the light sources 16,18 to emit radiation at a desired pattern or frequency. Such encoding orother temporal modulation of the radiation emitted by the light sources16, 18 may be accomplished by any known means such as, but not limitedto, modulating the current and/or voltage supplied to the light sources16, 18, or by passing the radiation emitted by the light sources 16, 18through an electro-optic, electro-acoustic, or other known modulatorprior to permitting the radiation to exit the target marking system 10.

For example, the controller 20 may control the light sources 16, 18 toemit a beam having a predetermined frequency signature. Such a frequencysignature may be repeated at predetermined intervals as desired.Alternatively, the controller 20 may control the light sources 16, 18 toemit one or more beams having a specified predetermined frequencypattern for as long as the beam is emitted. It is understood that suchperiodic frequency signatures or unique specified frequency patterns maybe randomly generated as is typical in known encoding applications. Suchcontrollers 20 may also be configured to communicate with, for example,controllers of other target marking system, or with other hardwareutilized in combat arenas, in order to synchronize the functionality ofthe respective light sources 16, 18 utilized in a particular targetmarking application. Thus, the controller 20 may enable the signature ofthe beam, pulse, signal, and/or other radiation emitted by the lightsources 16, 18 to be preset, and for the signature, wavelength,frequency, pulse pattern, and/or other characteristics of the emittedbeam to be easily tunable in the field and/or during use.

The housing 11 of the target marking system 10 may be, for example,substantially fluid tight, such that the light sources 16, 18,controller 20, and/or other components of the system 10 may be operablein wet conditions. In an exemplary embodiment, the system 10 may berated for substantially complete submersion in a liquid for a period ofa least 30 minutes. In such an exemplary embodiment, the liquid maycomprise, for example, fresh water or salt water. The system 10 may alsobe configured to withstand a substantial level of shock, vibration,and/or other contact typical of rugged use. For example, the system 10may be configured for use in harsh environments such as, for example,jungles, swamps, deserts, rocky terrain, and/or other law enforcement,combat, or self-defense environments.

Although not illustrated in FIG. 1, it is understood that the targetmarking system 10 may also include at least one selection deviceconfigured to enable the user to select which of the light sources 16,18 to utilize for a particular application. Such an exemplary selectiondevice may comprise a button, rotatable knob, and/or other operatorinterface configured to select one or more of the light sources 16, 18for use.

Although not shown in FIG. 1, the target marking system 10 may furtherinclude an activation device to enable the user to activate one or moreof the light sources 16, 18 during use. Such an activation device mayhave a configuration similar to a trigger or a depressible switch. Insuch an exemplary embodiment, the activation device may be configured toenergize and/or otherwise activate one or more of the light sources 16,18 in either a pulsed mode, a continuous mode, and/or other modeselected by the user. It is understood that the activation device and/orthe selection device may enable use of more than one light source 16, 18at the same time.

The power source 38 may be any source of power known in the art such as,for example, one or more batteries. In an exemplary embodiment, thepower source 38 may comprise a plurality of AA or CR-123 batteries. Thepower source 38 may be, for example, disposable and/or rechargeable, andthe power source 38 may be configured to supply power to one or morelasers, QCLs, and or other light sources 16, 18 of the type describedabove. As described above, the power source 38 may be operably connectedto the controller 20, the light sources 16, 18, the detector 14, thecooling element 22, and/or any of the other target marking systemcomponents described herein. In additional exemplary embodiments, thepower source 38 may comprise N-type batteries, and/or lithium-manganesedioxide batteries. Although FIG. 1 illustrates the power source 38 beingdisposed within the housing 11, in additional exemplary embodiments, thepower source 38 may be disposed outside of the housing 11. In anexemplary embodiment, the power source 38 may disposed on and/orotherwise mounted to the firearm 36 to which the target marking system10 is connected.

In an exemplary embodiment in which at least one of the light sources16, 18, comprises a QCL, a cooling element 22 may be disposed in thermalcontact with the QCL. Such a cooling element may be disposed within thehousing 11 and, in additional exemplary embodiments, such coolingelements may be disposed outside of the housing 11 such as, for example,on a portion of the firearm 36 to which the target marking system 10 isconnected. In any of the embodiments described herein, a portion of thecooling element 22 may be exposed to ambient conditions. Regardless ofits location, the cooling element 22 may be employed to maintain one ormore of the light sources 16, 18 described herein at a desirableoperating temperature. Certain configurations of the cooling element 22may require, for example, energy input. Thus, in an exemplaryembodiment, at least a portion of the cooling element 22 may be operablyconnected to the power source 38 and/or the controller 20.

The cooling element 22 may assist in cooling the QCL to a specifiedand/or desired operating temperature range. Additionally, the coolingelement 22 may assist in cooling, for example, at least a portion of thehousing 11 to a specified and/or desired operating temperature range.Such a portion of the housing 11 may include an internal compartment ofthe housing 11 and/or any desirable portion thereof. For example, thecooling element 22 may assist in cooling the QCL and/or a portion of thehousing 11 to approximately room temperature, or between approximately65 degrees Fahrenheit and approximately 75 degrees Fahrenheit. Forexample, the cooling element 22 may be either a passive device or anactive device. Exemplary passive cooling elements 22 may include, forexample, heat sinks, phase change elements, thermal conductors, heatpipes, radiators, and/or one or more fins configured to dissipatethermally energy from the QCL. In an exemplary embodiment, one or morecomponents of the cooling element may be made from highly thermalconductive materials such as thermal pyroelectric graphite, or the like.

Active cooling elements 22, on the other hand, may include thermalelectric coolers, Peltier modules, Sterling devices, and/or any otherlike cooling elements or devices known in the art. It is understood thatin additional exemplary embodiments, the cooling element 22 may beomitted even if one or more QCLs are employed.

It is understood that the firearm 36 may comprise any light, medium, orheavy weapon system, including any hand gun, rifle, or other automaticor semi-automatic weapon known in the art. Such firearms 36 may beutilized in, for example, combat, law enforcement, self-defense, orother like applications. The target 26 illustrated in FIG. 1 maycomprise any object at which the firearm 36 may be aimed and/or fired orotherwise discharged. Such targets may be animate objects, such ashumans or animals, or inanimate objects, such as, for example,automobiles, security structures, or other objects typically targeted inthe applications described herein.

The detector 14 may be any device or combination of devices configuredto receive beams, pulses, signals, and/or other like radiation emitted,scattered, reflected, and/or otherwise directed by a target 26 and tointerpret characteristics of the received radiation on a pixel-by-pixelbasis. For example, the detector 14 may comprise a focal plane arraysuch as, for example, a microbolometer array, or other like devicehaving an array of pixels. Such a microbolometer array may be cooled oruncooled depending on the desired application. In an additionalexemplary embodiment, the detector 14 may comprise a readout integratedcircuit or other like component configured to detect a temporallymodulated thermal input and produce an enhanced digital output signalbased on the detected thermal input. In an exemplary embodiment, thereadout integrated circuit may comprise at least a portion of thedetector 14 and/or the controller 20.

In an exemplary embodiment, radiation received by the detector 14 suchas, for example, re-emitted, reflected, and/or scattered radiation 28,74, 70 passing from the target 26 to the detector 14 may impinge uponthe detector 14, thereby heating a portion of the detector 14 andchanging the electrical resistance of the heated portion. Thisresistance change may be measured and processed by, for example, thecontroller 20 and/or the readout integrated circuit. For example, pixelsof the detector array may be heat sensitive, and may exhibit a change inresistance when light having a wavelength between approximately 8 μm andapproximately 20 μm or longer is incident thereon. This re-emitted,reflected, and/or scattered radiation 28, 74, 70 may be utilized tocreate an image of, for example, the portion or area 92 (FIG. 11) of thetarget 26 impinged upon by the radiation beam 24 emitted by the targetmarking system 10. The image of the area 92 may be shown on the display60 so as to be viewable by a user 62.

Thus, the detector 14 may comprise a thermal sensor having an array 96(FIG. 11) of pixels that can be controlled to look for, seek, identify,and/or otherwise detect radiation having a known, encoded,predetermined, and/or otherwise specified temporal modulation pattern.Such a detector 14 may be configured to identify such a pattern and codepixels in its array 96, on a pixel-by-pixel basis, based on the detectedpattern. The detector 14 may then send an input signal to the controller20 or other components of the readout integrated circuit for processing.The input signal may include information indicative of the resistance ofeach pixel of the detector 14 over time. Such information may include,for example, the intensity level detected by each pixel over time. Thecontroller 20 or other components of the readout integrated circuit maysend an output signal to the display 60 indicative of and/or otherwisecorresponding to the input signal. In an exemplary embodiment, theoutput signal may control the display 60 to modify the gain, contrast,brightness, color, and/or other characteristics of corresponding pixelsof the display 60.

The display 60 may illustrate the modulation detected by the detector 14in any manner that is easily identifiable by the user 62, regardless ofthe environment in which the system 10 is used. For example, the display60 may comprise a pixel array corresponding to the pixel array of thedetector 14. The pixel array of the display 60 may be configured todisplay a thermal image of the target 26. The pixels of the display 60displaying the portion or area of the target 26 impinged upon by thethermal beam 24 from the target marking system 10 may illustrate thepoint of impact of the beam 24 using, for example, red, green, yellow,orange, or other colors. Such pixel-by-pixel color-coding may enable theuser 62 to easily identify the point of impact when looking at thedisplay 60. Alternatively, one or more pixels of the display 60 mayblink, flash, or otherwise temporally modulate in any known easilyidentifiable way. As will be described in greater detail below, one ormore pixels of the display 60 may be controlled according to one or morecorresponding pixels of the detector 14. The detector 14 may furtherinclude additional display components to facilitate the pixel coding andtarget image display described herein.

The light sources 16, 18 may be controlled to emit radiation having apredetermined and/or specified temporal modulation pattern or signature,and such patterns or signatures may include periodic modulations orspecified frequency patterns. The detector 14 may be controlled toidentify any such temporal modulation patterns substantiallyinstantaneously. In addition, such temporal modulation patterns can berapidly and easily changed, using the controller 20 or other componentsof the systems 10 described herein, for operational security purposes.Such changes may occur, for example, during combat operations to reduceor eliminate the risk of enemy forces detecting the emitted, re-emitted,reflected, and/or scattered radiation 76, 28, 74, 70 discussed herein.

Thus, the components of the detector 14 may be controlled to seek,identify and/or look for, on a pixel-by-pixel basis, radiation havingone of the predetermined and/or specified temporal modulation patternsdiscussed above using a gating process, a phase locking process, and/orother known processes. In such a gating process, the controller 20 maycommunicate to the detector 14 that a beam, signal, pulse, and/or otherradiation has been emitted by the target marking system 10. In response,the detector 14 may attempt to locate and/or identify re-emitted,reflected, and/or scattered radiation 28, 74, 70 passing from the target26, on a pixel-by-pixel basis, for a fixed period of time. Such gatingprocesses may be initiated and/or otherwise effected due to a directelectrical connection between, for example, the controller 20 and thedetector 14. Alternatively, such gating processes may be initiatedand/or otherwise effected upon receipt of a wireless signal and/ortrigger. Such a wireless signal may be, for example, a blue tooth and/orother like signal, and at least one of the controller 20 and thedetector 14 may be configured to receive such a signal for effecting agating process.

In a phase locking process, on the other hand, the detector 14 may becontrolled to identify re-emitted, reflected, and/or scattered radiation28, 74, 70 passing from the target 26 having a predetermined and/orspecified temporal modulation pattern without being notified that thetarget marking system 10 has emitted a beam, signal, pulse, and/or otherradiation. Instead, the detector 14 may detect and/or process allradiation passing thereto, and may determine whether any of the incomingradiation exhibits, for example, the predetermined and/or specifiedtemporal modulation pattern, or other identifiable characteristics. Ifthe incoming radiation does exhibit such a pattern or characteristic,the display 60 may be controlled to display, for example, a thermalimage of the target 26 with the impact point of the thermal beam emittedby the target marking system 10 being color-coded in the image. It isunderstood that the gating, phase locking, and/or other like processesdescribed herein may be employed on a pixel-by-pixel basis inembodiments of the detector 14 having pixel arrays or other likecomponents. Moreover, the gating, phase locking, and/or other likeprocesses described herein may be performed without performing the beamshaping processes described herein.

With continued reference to FIG. 1, the optics assembly 12 may compriseone or more optical components such as, for example, one or more lenses,windows, beam splitters, mirrors, prisms, beam combiners, diffractiongratings, and/or other known optical components configured to direct,condition, shape and/or otherwise control the passage of radiationtherethrough. For example, the optics assembly 12 may be configured tocollect as much re-emitted, reflected, and/or scattered radiation 28,74, 70 as possible and to direct the collected radiation 28, 74, 70 tothe detector 14. Such radiation may include, for example, any beams,pulses, signals, and/or other radiation emitted by the light sources 16,18 in the thermal and/or other spectral band, as well as the re-emitted,reflected, and/or scattered radiation 28, 74, 70 received from thetarget 26. As described above, the target marking system 10 may comprisea single optics assembly 12 that is shared by the light sources 16, 18and the detector 14. The optics assembly 12 may include, for example,one or more lenses, apertures, filters, modulators, and/or other opticalcomponents to facilitate the beam shaping techniques described herein.The optics assembly 12 may be, for example, a focal power changer, acamera objective, a catadioptric lens, or any other known lightcollection system. In an additional exemplary embodiment, the opticsassembly 12 may comprise any known zoom system.

FIG. 2 illustrates an exemplary optics assembly 12 of the presentdisclosure. As shown in at least FIGS. 2-6, exemplary embodiments of thetarget marking systems 10, 100 described herein may employ multiplelight sources 16, 18, 19 to form the emitted beam 24. The fusion and/orintegration of multiple light sources in this way may assist inmaximizing the total power, intensity, heat, energy, and/or otherquantifiable metrics of the radiation directed to a target 26 by thetarget marking system 10, 100. In the embodiment shown in FIG. 2, a beamcombiner 40 may be utilized to combine two orthogonal beams of radiation24 a, 24 b. In such an exemplary embodiment, the beam combiner 40 maybe, for example, a polarizing beam combiner such as, for example, aBrewster window or other like device. In an additional exemplaryembodiment, the beam combiner 40 may comprise any known beam splitter.The beam combiner 40 may be configured to combine beams 24 a, 24 bhaving different polarities, regardless of wavelength, and to emit suchbeams 24 a, 24 b collinearly as a single emitted beam 24. Such anexemplary embodiment may be particularly useful in maximizing the powerof the emitted beam 24 impinging upon a target 26 at relatively closedistances.

As shown in FIG. 2, beam 24 a emitted by the light source 16 may belinearly polarized such that the electrical field of the beam 24 a isoriented in a direction substantially orthogonal to the path of the beam24 a (substantially into and substantially out of the page). The lightsource 18, on the other hand, may emit beam 24 b characterized by anelectrical field oriented in a direction substantially perpendicular tothe path of the beam 24 b. The beams 24 a, 24 b may pass throughrespective lenses 42, 44 disposed optically upstream of the beamcombiner 40. The lenses 42, 44 may be, for example, any catadioptriclenses, refracting lenses, reflecting lenses, diffracting lenses,collimating lenses, and/or other lenses known in the art. Upon passingthrough the lens 42, the beam 24 a may impinge upon a mirror 38 and/orother like optical component. The mirror 38 may direct the beam 24 aonto the beam combiner 40. Alternatively, the light source 16 may bedisposed at any desirable angle relative to the beam combiner 40 suchthat the beam 24 a may be directed to impinge upon the beam combiner 40without the use of a mirror 38. In such an exemplary embodiment, themirror 38 may be omitted.

The light source 18 may direct the beam 24 b onto the lens 44, and thelens 44 may direct the beam 24 b to impinge upon the beam combiner 40.The different surface coatings, shapes, sizes, and/or otherconfigurations of the beam combiner 40 may enable the beam combiner 40to perform various desired beam combination functions. For example, thebeam combiner 40 may be configured to reflect light and/or other formsof radiation having a first polarization and to transmit light and/orother forms of radiation having a second polarization. Such reflectionand/or transmission functions may be performed by the beam combiner 40regardless of the respective wavelengths of the various impinging beams.As shown in FIG. 2, the beam combiner 40 may reflect the beam 24 adirected by the mirror 38 and having a first polarization. The beamcombiner 40 may also transmit the beam 24 b directed by the lens 44 andhaving a second polarization different from the polarization of beam 24a. In this way, the beam combiner 40 may emit beams 24 a, 24 bcollinearly as the single emitted beam 24. The emitted beam 24 may benarrower, smaller in diameter, and/or more powerful than, for example,combined or overlapping non-collinear beams emitted by other exemplarytarget marking systems.

FIG. 3 illustrates an exemplary embodiment in which a plurality of lightsources 16, 18, 19 are employed to emit an emitted beam 24 that is madeup of a combination of non-collinear beams 24 a, 24 b, 24 c. It isunderstood that, in such an exemplary embodiment, any desired number oflight sources may be employed, and in additional exemplary embodiments,two or more light sources may be used. In such exemplary embodiments,increasing the number of light sources utilized may result in anincrease in the overall power, diameter, and/or other quantifiableoptical characteristics of the resulting emitted beam 24. Thus, becausesuch an exemplary embodiment may be scalable in nature, utilizing aplurality of light sources in the manner illustrated in FIG. 3 may beparticularly advantageous for impinging the emitted beam 24 upon atarget 26 disposed at relatively greater distances d as compared to theembodiment shown in FIG. 2. The exemplary embodiment of FIG. 3 may beparticularly well suited in applications in which the overall diameterof the emitted beam 24 is less critical. For example, the exemplaryconfiguration illustrated in FIG. 3 may be acceptable in applications inwhich an emitted beam 24 has a diameter that is approximately threetimes the size of a single beam 24 a, 24 b, 24 c. As shown in FIG. 3,the overall diameter a of the emitted beam 24 may be slightly less thanthe sum of the diameters of the individual beams 24 a, 24 b, 24 c inembodiments in which the beams 24 a, 24 b, 24 c have some degree ofoverlap. The overall diameter α of the emitted beam 24 may be enlargedand/or reduced based on the spacing of the respective light sources 16,18, 19.

As shown on FIG. 3, the respective beams 24 a, 24 b, 24 c may be passedthrough one or more lenses 42, 44, 45, respectively. The lenses 42, 44,45 may be structurally similar to the lenses 42, 44 described above withregard to FIG. 2. For example, the lenses 42, 44, 45 may be configuredto collimate the respective beams 24 a, 24 b, 24 c passing therethrough.Notwithstanding such collimation, each individual beam may exhibit asmall degree of beam divergence represented by θ in FIG. 3. In such anexemplary embodiment, the beam divergence θ may be substantially equalto the wavelength λ of the respective beam 24 a, 24 b, 24 c divided bythe respective diameter D of the lens 42, 44, 45. As described herein,in exemplary embodiments, the wavelength of the individual beams 24 a,24 b, 24 c may be between approximately 2 μm and approximately 30 μm. Inthe exemplary embodiment shown in FIG. 3, the individual beams 24 a, 24b, 24 c may be combined regardless of wavelength or polarization. Forexample, the individual beams 24 a, 24 b, 24 c may have the samewavelength, or at least one of the beams may have a wavelength differentfrom the remaining beams. In addition, the individual beams 24 a, 24 b,24 c may have the same polarization, or at least one of the beams mayhave a different polarization than the remaining beams.

As shown in FIG. 4, in an additional exemplary embodiment, two or moreindividual beams having different wavelengths may be combined byexemplary optics assemblies 12 of the present disclosure, and such beamsmay have the same polarization or different polarizations. For example,individual beams 24 a, 24 b, 24 c may be emitted by respective lightsources 16, 18, 19, and passed through respective lenses 42, 44, 45. Asdescribed above, in an exemplary embodiment, the lenses 42, 44, 45 mayassist in substantially collimating the individual beams 24 a, 24 b, 24c as they pass therethrough. In addition, each of the beams 24 a, 24 b,24 c may have different respective wavelengths, λ₁, λ₂, λ₃. In such anexemplary embodiment, two or more beams may be combined using one ormore beam combiners and, as shown in exemplary FIG. 4, the first beam 24a having a first wavelength λ₁ may be combined with the third beam 24 chaving a wavelength λ₃ using a wavelength beam combiner 46. Thewavelength beam combiner 46 may be configured to combine two or morebeams of radiation such as, for example, light having differentwavelengths, regardless of the polarization of the impinging beams. Thethickness of the surface coatings and/or the number of surface coatingsapplied to the beam combiner 46 may be controlled and/or selected toreflect and/or transmit two or more beams in any desired way. Forexample, as shown in FIG. 4, the beam combiner 46 may be configured totransmit beams having a wavelength λ₃ and to reflect beams having awavelength λ₁. As a result, when beam 24 c impinges upon a first surfaceof the beam combiner 46 and beam 24 a impinges on a second oppositesurface of the beam combiner 46, the beam combiner 46 may emit a singlesubstantially collinear beam including radiation characterized by bothwavelengths λ₁ and λ₃. Such a beam 24 d may then impinge upon a firstsurface of a second beam combiner 48. The beam combiner 48 may be, forexample, substantially structurally similar to the beam combiner 46described above. In such an exemplary embodiment, the beam combiner 48may be configured to reflect radiation having wavelengths λ₁ and λ₃ andto transmit radiation having a wavelength λ2. Accordingly, as shown inFIG. 4, the beam combiner 48 may permit the beam 24 b having awavelength λ₂ to pass therethrough, and may also reflect the beam 24 demitted by beam combiner 46. Accordingly, the beam combiner 48 may forman emitted beam 24 made up of beams 24 d and 24 b aligned substantiallycollinearly. The emitted beam 24 may include each of the wavelengths λ₁,λ₂, λ₃.

In additional exemplary embodiments, individual beams from a pluralityof light sources may also be combined utilizing one or more diffractiongratings or other like optical components. For example, as shown in FIG.5, individual beams 24 a, 24 b, 24 c may be emitted by respective lightsources 16, 18, 19, and passed through respective lenses 42, 44, 45, asdescribed above with regard to FIG. 4. However, instead of utilizingbeam combiners 46, 48 to combine such individual beams, a diffractiongrating 50 may be employed to form a single emitted beam 24. Asdescribed with regard to FIG. 4, each of the individual beams 24 a, 24b, 24 c may have the same polarization or different polarizations. Inaddition, each of the individual beams 24 a, 24 b, 24 c may have thesame or different wavelengths. Accordingly, the emitted beam 24 mayinclude each of the wavelengths of the individual beams 24 a, 24 b, 24c. In addition, the individual beams 24 a, 24 b, 24 c may be orientedand/or angled in any desirable way relative to a surface normal 94 ofthe diffraction grating 50. In addition, one or more lenses, windows,and/or other optical components may be employed by the exemplary opticsassembly 12 illustrated in FIG. 5 to assist in orienting the individualbeams 24 a, 24 b, 24 c relative to one another such that a substantiallycollinear emitted beam 24 may be produced by the diffraction grating 50.

In still another exemplary embodiment, one or more optical componentssuch as a prism, mirror, or the like may be utilized to capture,condition, redirect, and/or otherwise manipulate radiation emitted byone or more light sources of the type described herein. For example, asshown in FIG. 6, one or more of the light sources utilized by thesystems 10, 100 may emit radiation in more than one direction. Anexemplary light source 16 may emit a first individual beam 24 a passingin a first direction shown by arrow 96, and a second individual beam 24b passing in a second opposite direction shown by arrow 98. Each of thebeams 24 a, 24 b may be directed to pass through respective lenses 42,44, and the beam 24 b may impinge upon one or more mirrors or a prism 52disclosed optically downstream of the lens 44. The prism 52 may redirectthe beam 24 b to be substantially parallel to the first beam 24 a. Inthis way, the optics assembly 12 may be configured to maximize theamount of emitted radiation utilized by the system 10, 100. Such aconfiguration may result in an increase in the power, intensity, and/orother quantifiable characteristics of the emitted beam 24. In theexemplary embodiment of FIG. 6, the individual beams 24 a, 24 b may notbe collinear upon passing from the optics assembly 12. However, theindividual beams 24 a, 24 b may be substantially parallel to each otherand may at least partially overlap. It is also understood that utilizinga prism 52 in the exemplary embodiment of FIG. 6 may assist inmaintaining the parallel relationship of the individual beams 24 a, 24b, and may reduce the complexity in manufacturing, for example, theoptics assembly 12. For instance, because a prism 52 may be asubstantially one-piece design, vibrations, agitations, and/or othermovement of the optics assembly 12 may have very little effect on theparallel relationship between the beams 24 a and 24 b. On the otherhand, replacing the prism 52 with one or more mirrors may make it moredifficult to maintain, for example, a substantially parallel orientationbetween the individual beams 24 a, 24 b when the optics assembly 12 isshaken, jarred, vibrated, and/or otherwise moved. Such variations mayoccur due to relative movement between, for example, the one or moremirrors or the other optical components of the optics assembly 12 duringuse.

Exemplary embodiments of the present disclosure may also employ variousthermal management schemes to account for the heat and other energyproduced by the one or more light sources described herein. As discussedabove, light sources such as QCLs and the like may give off asubstantial amount of heat during operation. At the same time, suchlight sources may have an optimal operating temperature range withinwhich efficiency is maximized. Accordingly, maximizing the efficiency ofthe systems 10, 100 described herein may require maintaining the one ormore light sources 16, 18, 19 within their respective optimal operatingtemperature range. Accordingly, each of the light sources describedherein may be thermally, physically, and/or otherwise operably connectedto the cooling element 22 described above. In exemplary embodiments, thecooling element 22 may comprise one or more different active and/orpassive cooling components configured to assist in removing heat fromthe respective light source to which it is connected. Removing heat inthis way may be particularly advantageous when utilizing, for example,QCLs or other like light sources because as such light sources increasein temperature, these light sources become less efficient. Moreover,once a maximum operating temperature is exceeded, such light sources maycease to function. As described above, one or more active coolingelements 22 may be thermally connected to such light sources to assistin reducing the temperature thereof. However, such cooling elements 22may require power in order to function. In addition, active coolingelements 22 may also produce heat during use. As a result, such activecooling components may not be suitable for use in all applications.

In additional exemplary embodiments, the cooling element 22 may be apassive device, and may include one or more passive cooling componentsthermally connected to the one or more light sources 16, 18, 19 toassist in removing heat therefrom. Such components may rely on, forexample, diffusion to pull thermal energy away from the light sources16, 18, 19, thereby cooling the respective light sources and optimizingtheir operational efficiency.

As shown in FIG. 7, an exemplary cooling element 22 may include one ormore thermal conductors 54, 56 thermally connected to a light source 16.The cooling element 22 may also include one or more componentscomprising phase change material or the like. Such a phase changematerial component 72 may also be thermally connected to light source16. As shown in FIG. 7, in an exemplary embodiment, the phase changematerial component 72 may be thermally connected to the light source 16via one or more of the thermal conductors 54, 56. Alternatively, thelight source 16 may be directly connected and/or coupled to the phasechange material component 72. The cooling element 22 may also includeone or more additional cooling elements such as, for example, passivecoolers 80, 82. Such passive coolers 80, 82 may be thermally connectedto the respective thermal conductors 54, 56. Alternatively, such passivecoolers 80, 82 may be directly connected and/or coupled to, for example,the light source 16 and/or the phase change material component 72. Inadditional exemplary embodiments, the passive coolers 80, 82 may bethermally connected to each other, and in further exemplary embodiments,the thermal conductors 54, 56 may be thermally connected to each other.It is understood that the passive coolers 80, 82 may comprise any of theheat sinks, radiators, fins, and/or other passive cooling componentsdescribed above with regard to the cooling element 22. In addition, thethermal conductors 54, 56 may comprise any highly thermally conductivematerial known in the art such as, for example, copper, aluminum,titanium, and the like. In addition, one or more of the thermalconductors 54, 56 may comprise thermal pyroelectric graphite and/orother like materials. Such materials may be highly thermally conductiveand may be utilized to enhance the thermal conductivity of one or morecomponents of the cooling element 22. For example, at least one of thethermal conductors 54, 56 may be a highly thermally conductive plate orother like structure comprising an alloy formed by combining thermalpyroelectric graphite with copper.

As illustrated by the graph in FIG. 7, during operation the temperatureof the light source 16 may increase from a substantially ambienttemperature to a given operating temperature of the light source 16.Such an increase is illustrated in Section A of the graph. During thistime, the light source 16 may dissipate heat to the first passive cooler80 via the thermal conductor 54. The light source 16 may also dissipateheat to the phase change material component 72 via the thermal conductor54, and as a result, the temperature of the phase change materialcomponent 72 may also rise. As illustrated in Section A of the graph,during continued operation, the temperature of the light source 16 maycontinue to rise and, during this time, the ability of the passivecooler 80 to dissipate the heat generated by the light source 16 may beexceeded. In such an exemplary embodiment, the phase change temperature(T_(change)) of the phase change material component 72 may be chosenand/or otherwise desirably selected such that the phase change materialtherein does not change phase until the amount of heat generated by thelight source 16 exceeds the heat dissipation capabilities of the passivecooler 80. Once such a temperature (T_(change)) is reached, the phasechange material within the phase change material component 72 may beginto change phase (for example, from solid to liquid). As shown by SectionB of the graph illustrated in FIG. 7, during this phase change processthe temperature of the light source 16 may remain substantiallyconstant, and this constant temperature (T_(change)) may be maintaineduntil such a phase change is completed. Once complete, the phase changematerial of the phase change material component 72 may no longer becapable of absorbing energy from the light source 16. In addition, thethermal energy stored/absorbed by the phase change material must beremoved before the phase change material is capable of again absorbingheat. Accordingly, the thermal conductor 56 may be employed to transmitsuch stored thermal energy from the phase change material component 72to the passive cooler 82, whereby such stored thermal energy can beproperly dissipated. The passive coolers 80, 82 may be disposed withinand/or external to the housing 11 of the assembly 10, 100 (FIG. 1, FIG.12).

As shown in Section C of the graph illustrated in FIG. 7, while heat isbeing removed from the phase change material component 72, thetemperature of the light source 16 may continue to rise until themaximum operating temperature (T_(max)) of the light source 16 isreached. Upon reaching this temperature, the light source 16 may nolonger function, and may be deactivated in order to facilitate coolingthereof. Such a cooling phase may be represented by Section D of thegraph illustrated in FIG. 7. In an exemplary embodiment, while the lightsource 16 is allowed to cool, one or more components of the coolingelement 22 may again begin to dissipate and/or otherwise remove heatfrom the light source 16. As a result, the slope of the curverepresented in Section D of the graph may be steeper than, for example,the slope of the curve in Section C between T_(change) and T_(max).Alternatively, the elevated temperature of one or more components of thecooling element 22 may extend the required cooling time of the lightsource 16 and/or may otherwise extend the time required to cool thelight source 16. Such an exemplary extension of required cooling time isillustrated by Section E of the graph shown in FIG. 7. In an exemplaryembodiment, once the phase change material component 72 reaches a stateor temperature in which its phase change material is again capable ofabsorbing thermal energy, the phase change material component 72 maycontinue absorbing heat from the light source 16 and may again assist inmaintaining the light source 16 at the temperature T_(change) as shownin Section E.

In additional exemplary embodiments, it may be desirable and/oradvantageous to dissipate and/or otherwise remove heat from one or moreof the light sources described herein in a directional manner. Forexample, the size, shape, and/or other configurations of the housing 11(FIG. 1, FIG. 12) and/or other packaging components may not allow for adirect physical connection between, for example, one or more of thelight sources 16 and the various components of the cooling element 22.In such exemplary embodiments, the cooling element 22 may employ one ormore components configured to remove thermal energy and/or other energyfrom the one or more light sources described herein and transmit suchenergy, in a directional manner, to the phase change material component72, passive coolers 80, 82 and/or other components of the coolingelement 22.

For example, as illustrated in FIG. 8, one or more of the light sources16 may be thermally, physically, and/or otherwise connected to a heatpipe 84 and/or other like directional thermal conductor known in theart. Such a heat pipe 84 may assist in directionally transferringthermal energy over relatively large distances. For example, one or moreheat pipes 84 may be utilized to transmit thermal energy from one ormore light sources of the type described herein upwards of,approximately, 24 inches. Such heat pipes 84 may be substantially solidstate passive cooling devices having relatively high thermalconductivity characteristics. Accordingly, the one or more heat pipes 84described herein may be utilized in combination with or in place of theone or more thermal conductors 54, 56 described above. Moreover,exemplary embodiments of the heat pipe 84 may have a greater thermalconductivity in a first direction than in a second direction. Suchdirectional thermal conductivity of the heat pipe 84 may be due to, forexample, the molecular structure of the materials utilized to form theheat pipe 84. In addition, the heat flow dynamics of the structures usedin constructing the heat pipe 84 may contribute to its directionalthermal conductivity characteristics. For example, the heat pipe 84 maycomprise two or more substantially concentric tubes enablingrecirculation of water, Freon, or other known heat dissipation materialsto achieve any desired degree of directional thermal conductivity. As aresult, the heat pipe 84 may enable the user to control the direction inwhich thermal energy flows from the components to which the heat pipe 84is thermally connected. For example, as shown in FIG. 8, as the lightsource 16 begins to heat, the heat pipe 84 may draw thermal energy fromthe light source 16 and transmit it in the direction of arrow 96 to thephase change material component 72. In addition, one or more passivecoolers 80, 82 may be thermally connected to the heat pipe 84 and/or thephase change material component 72, and may be configured to assist indissipating heat therefrom.

The phase change material component 72 described herein may include anyphase change material known in the art. Such phase change material maybe, for example, a substantially solid wax, oil, or other likesubstantially organic or inorganic material having a capacity to absorbheat and to change phase once a threshold phase change temperature(T_(change)) has been reached. For example, a phase change materialhaving a heat capacity between approximately 100 joules per gram andapproximately 300 joules per gram may be employed by the exemplarycooling elements 22 described herein. In exemplary embodiments, phasechange materials such as Bees Wax with a melting point of approximately61.8 degrees C. and a latent heat of approximately 177 Joules per gram,and/or N-Octacosane with a melting point of approximately 61.4 degreesC. and a latent heat of approximately 134 joules per gram may be used.Such materials may facilitate maintaining the one or more light sourcesthermally connected thereto at a substantially constant operatingtemperature for a predetermined period of time. For example, asillustrated in FIG. 7, the temperature of the light source 16 may bemaintained at approximately T_(change) while the phase change materialof the phase change material component 72 completes its phase change.Because such material may change from, for example, solid to liquid, thephase change material component 72 may comprise a substantially enclosedstructure configured to safely house liquid phase change material. Thephase change material component 72 may comprise a porous sponge-likefoam, mesh, grid, honeycomb, or other like structure to assist inretaining such phase change material in both the solid and liquid phase.The phase change material component 72 may also assist in forming athermally conductive path between the phase change material disposedtherein and the heat pipe 84, passive coolers 80, 82, thermal conductors54, 56, and/or other components of the target marking system 10, 100.

As described above, extended use of the one or more light sources 16,18, 19 described herein may drain power from the one or more powersources 38 operably connected thereto. Moreover, such extended use mayreduce the thermal energy removal capacity of one or more coolingelement components such as, for example, the phase change materialcomponent 72. Accordingly, in exemplary embodiments it may be useful toremove and/or replace one or more such cooling element components inconjunction with removal and/or replacement of one or more power sourcecomponents. In an exemplary embodiment in which the power source 38comprises one or more removable and/or replaceable batteries, it may beconvenient to remove and/or otherwise replace the phase change materialcomponent 72 at the same time as such batteries. Accordingly, as shownin FIG. 9, at least one component of the cooling element 22 may becoupled to a removable component of the power source 38. For example,the phase change material component 72 may be coupled to a replaceablebattery of the power source 38 such that removal of the replaceablebattery results in removal of the phase change material component 72.Because substantially completely draining the stored electrical energyof such a battery will often times coincide with the phase changematerial within the phase change material component 72 having reachedits thermal energy storage limit, replacing both such components at thesame time may result in more streamlined operation of the target markingsystem 10, 100.

In another exemplary embodiment of the present disclosure, the opticsassembly 12 may include one or more components configured to assist inaligning, for example, the light sources 16, 18, 19 relative to oneanother. For example, as shown in FIG. 10, the optics assembly 12 mayinclude one or more adjustable alignment windows 88, 90 disposed in theoptical path of beams 24 a and 24 b, respectively. Such alignmentwindows 88, 90 may be, for example, any lens, mirror, grating, prism,zero power optic, and/or other known optical component. Such alignmentwindows 88, 90 may be configured to, for example, manipulate, shift,angle, and/or otherwise change the direction of a collimated beam. Forexample, each alignment window 88, 90 may be independently tuned,rotated, adjusted, and/or otherwise manipulated by the user of thesystem 10, 100 to assist in aligning multiple light sources 16, 18, 19with respect to one another. As shown by the arrows depicted in FIG. 10,in an exemplary embodiment, each of the alignment windows 88, 90 may berotatable clockwise and counterclockwise to facilitate inter-alignmentof the beams 24 a, 24 b. Additionally and/or alternatively, alignmentwindows 88, 90 may be tipped and/or tilted in any desirable direction tofacilitate inter-alignment of the beams 24 a, 24 b. Such alignment maybe performed optically upstream, for example, an additional optic 86 ofthe optics assembly 12. The optic 86 may be, for example, a zero poweroptic, a window, a lens, and/or other like optical component useful indirecting an emitted beam 24 in the direction of a target 26.

Additional structural components such as, for example, threaded rods,screws, bolts, knobs, thumbscrews, and the like may be utilized toassist in rotating the alignment windows 88, 90 with respect to oneanother, and with respect to the optic 86. Such additional componentsmay facilitate the fine tuning of the optics assembly 12 as desired.Such tuning components may be accessible on an exterior of the housing11 (FIG. 1, FIG. 12) such that the user may easily fine tune the opticsassembly 12 during and/or prior to use. Such alignment windows 88, 90may be useful in inter-alignment of the various light sources 16, 18,19, and may also useful in steering any of the collinear emitted beams24 described herein. In addition, once each of the windows 88, 90 havebeen properly positioned for such inter-alignment, the windows 88, 90may then be aligned and/or otherwise manipulated, in unison, foraligning the collinear emitted beam 24 with, for example, a barrel ofthe firearm 36 for target aiming purposes. Any of the thumbscrews,knobs, or other additional structural components described above may beutilized for such in unison manipulation.

Due to the inefficiencies inherent in many known light sources, and alsodue to the limitations on available power in hand-held and/or other liketarget marking systems, it may be advantageous to employ one or morecontrol strategies designed to minimize and/or eliminate unused outputor operation of the system components described herein. For example,target marking system users may energize the one or more light sourcesemployed therein substantially constantly. Such substantially constantactivation may result in the constant light source output depicted inthe graph shown in FIG. 11. Exemplary systems may also control adetector 14 to substantially constantly scan for, for example,re-emitted, reflected, and/or scattered radiation 28, 74, 70 (FIG. 1,FIG. 12). The detector may scan for such radiation on a pixel-by-pixelbasis, and such scanning may occur sequentially along, for example,various rows of a pixel array within the detector 14 and/or the display.Such an exemplary array 96 is illustrated in FIG. 11. The array 96 maycapture an image of substantially the entire target 26, and the array 96may image a scene or area that is significantly larger than the areacovered by the relatively small diameter emitted beam 24. Thus, althoughthe detector 14 may continuously scan for the radiation 28, 74, 70sequentially along pixel rows 1-9 illustrated in FIG. 11, the detector14 may not actually capture, detect, and/or image the area 92 of thetarget 26 impinged upon by the emitted beam 24 until rows 4 and 5 arescanned. Based on this sequential scanning function of the detector 14,activating the one or more light sources 16, 18, 19 to produce anemitted beam 24 during the time periods where the detector 14 isscanning, for example, pixel rows 1-3 and 6-9 may result in unused lightsource operation because, even if the emitted beam 24 accuratelyimpinges upon the target 26, the detector 14 will not be scanning pixelrows 4 and 5 during these time periods.

In an exemplary embodiment, one way of reducing the power requirementsof the target marking system 10, 100 may be to reduce the duty cycle ofthe one or more light sources 16, 18, 19 such that the emitted beam 24is only generated during the time period(s) where the one or more pixelrows corresponding to the area 92 of the target 26 impinged upon by theemitted beam 24. For example, in an exemplary method of controlling theone or more light sources 16, 18, 19 described herein, the light sourcesmay be energized and/or otherwise activated only when the detector 14 isscanning such corresponding pixel rows. As explained above, the lightsource output graph shown in FIG. 11 illustrates an exemplary embodimentin which a light source 16, 18, 19 is operated throughout the entirescanning time of the detector 14. As indicated by the shaded regions 1-3and 6-9, the energy expended in producing an emitted beam 24 duringthese time periods may be substantially unused since the detector 14 isonly able to image the area 92 when scanning in pixel rows 4 and 5. Bytriggering, synching, phase locking, and/or otherwise keying theactivation of the light source 16, 18, 19 to the scanning cycle of thedetector 14, the user may be able to substantially reduce the operatingtime of the light sources 16, 18, 19. Such reduced operating time mayresult in a corresponding reduction in thermal energy generation andpower consumption. As a result, such a control strategy may reduce thedemands on cooling element 22 and on power source 38, and may greatlyenhance the operability of the system 10, 100.

In addition to the control methods discussed above, the controller 20,power source 38 and/or other components of the system 10, 100 describedherein may be programmed, operated, controlled, and/or otherwiseemployed to provide any desired voltage to the one or more light sources16, 18, 19. Such components may utilize any of a variety of controlcircuits and/or topographies to facilitate such control. For example,the systems 10, 100 described herein may provide a substantiallyconstant current and/or substantially constant input power to the one ormore light sources 16, 18, 19. Alternatively and/or in addition, thecontroller 20 may control the light sources utilizing any known feedbackloop, and may drive the respective light sources to produce asubstantially constant output power. Such a drive control strategy wouldrequire use of suitable sensors and/or other known feedback loop controlcomponents. In still another exemplary embodiment, the one or more lightsources 16, 18, 19 may be driven in order to maintain a substantiallyconstant laser temperature. In such an exemplary embodiment, one or moretemperature sensors may be employed in a feedback loop employed by thecontroller 20.

It is further understood that the systems 10, 100 described herein mayutilize any type of switched mode power supply, voltage regulation,and/or other circuit topography known in the art. Such circuittopographies may include isolated converters and/or non-isolatedconverters. For example, the controller 20, power source 38, and/orother components of the systems 10, 100 may include a drive circuitconfigured to supply voltage to the one or more light sources 16, 18,19. Such a drive circuit may include one or more non-isolated converterssuch as buck converters, boost converters, buck-boost converters,split-pi converters, Ćuk converters, single-ended primary inductorconverters, Zeta converters, and/or charge pump converters.Alternatively, and/or in addition, such a drive circuit may include oneor more isolated converter circuits, and such circuits may include oneor more transformers configured to produce a higher or lower voltagethan that inputted to the transformer. Such isolated converters mayinclude, for example, SIPEX converter, an inverting converter, afly-back converter, a ringing choke converter, a half-forward converter,a forward converter, a resonate forward converter, a push-pullconverter, a half-bridge converter, a full-bridge converter, a resonatezero voltage switched converter, and/or an isolated Ćuk converter. Anyor all of the above converter circuit typographies may be utilized withand/or otherwise employed by the constant current, constant input power,constant output power, or constant temperature control schemes describedabove.

For example, as shown in FIG. 13, a drive circuit 21 of the controller20 may include a first converter 102 connected in series with a secondconverter 104, and a capacitor 106 connected between the first andsecond converters 102, 104. The detector 14, display 60 and othercomponents of the exemplary target marking system 10, 100 describedabove have been omitted from FIG. 13 for ease of description.

The first and second converters 102, 104 may be the same type ofelectrical converter or, alternatively, the converters 102, 104 may bedifferent types of electrical converters. For example, one or both ofthe first and second converters 102, 104 may comprise any of theisolated or non-isolated converters described above. In an exemplaryembodiment, the first converter 102 may be configured to charge thecapacitor 106 and/or maintain a voltage of the capacitor 106 betweenapproximately 2 volts and approximately 8 volts while the one or morelight sources 16, 18 emits the beam 24. In an exemplary embodiment, thefirst converter 102 may assist in charging the capacitor 106 toapproximately 5 volts before the beam 24 is emitted. In order tomaintain such desired voltage levels in the capacitor 106 before and/orwhile the beam 24 is emitted, the first converter 102 may comprise abuck converter if the voltage of the power source 38 is greater than thevoltage stored in the capacitor 106. Alternatively, in order to maintainsuch voltage levels in the capacitor 106 the first converter 102 maycomprise a boost converter if the voltage of the power source 38 is lessthan the voltage stored in the capacitor 106. In still another exemplaryembodiment, the first converter 102 may comprise a buck-boost converterin applications in which the voltage of the power source 38 may begreater than or less than the voltage stored in the capacitor 106.

In any of the embodiments described herein, the first converter 102 maybe configured to draw a substantially constant current from the powersource 38 while the one or more light sources 16, 18 emits the beam 24.The first converter 102 may be configured to direct such a substantiallyconstant current from the power source 38 to the capacitor 106. Bydirecting such a constant current to the capacitor 106, the firstconverter 102 may assist in maintaining the capacitor 106 at asubstantially constant voltage, such as a voltage between approximately2 volts and approximately 8 volts, as described above. It is understood,however, that as the beam 24 is emitted, the capacitor 106 may dischargeat least a portion of the stored voltage. For example, the capacitor 106may discharge approximately ⅔ of the stored voltage during each pulse ofthe emitted beam 24. The amount of stored voltage that is discharged bythe capacitor 106 may depend upon, for example, the pulse width of thebeam 24, the output power of the beam 24, and/or other characteristicsof the beam 24 and/or the light sources 16, 18. The capacitor 106 may beany type of capacitor and/or inductor known in the art, and in anexemplary embodiment, the capacitor 106 may comprise a single 0.15capacitor having a capacity of at least approximately 5 volts.

The second converter 104 may comprise any of the above converter types,and the second converter 104 may be configured to convert the voltageand/or energy stored in the capacitor 106 to a desired voltage useful indriving the one or more light sources 16, 18. It is understood that inexemplary embodiments in which one of the light sources 16, 18 comprisesan IR semiconductor laser, such a corresponding desired voltage may bebetween approximately 1.5 volts and approximately 2.5 volts. Inadditional exemplary embodiments in which one of the light sources 16,18 comprises a QCL, such a corresponding desired voltage may be betweenapproximately 12 volts and approximately 14 volts. In an exemplaryembodiment, the second converter 104 may be selectively enabled and/ordisabled to pulse the beam 24 emitted by the one or more light sources16, 18. In still further exemplary embodiments, the second converter 104may be controlled in response to, for example, an output power of thebeam 24, and/or in response to an operating characteristic of one ormore of the target marking system components. In such an exemplaryembodiment, the second converter 104 may maintain the output power ofthe beam 24 substantially constant. For example, the second converter104 may assist in maintaining an output power of each pulse of a pulsedemitted beam 24 substantially constant, and the operation of the secondconverter 104 may be controlled in response to the output power of eachpulse of the pulsed beam 24. Such a control strategy may be open-loop orclosed-loop in nature.

The drive circuit 21 may further comprise one or more switches 108connected in series with the one or more light sources 16, 18 tofacilitate pulsing of the beam 24. Such switches 108 may comprise, forexample, a MOSFET switch and/or any other like switching device. Inexemplary embodiments in which the drive circuit 21 comprises a switch108, it is understood that the second converter 104 may be substantiallycontinuously enabled during operation and the switch 108 may beselectively controlled to pulse the beam 24. Alternatively, the switch108 may be omitted, and the beam 24 may be pulsed using the secondconverter 104 and/or other components of the drive circuit 21 and/or thecontroller 20.

The exemplary drive circuit 21 illustrated in FIG. 13, and thevariations described above, represents an improvement over current lessefficient laser drive circuit designs. For example, typicalbattery-powered laser drive circuits may employ a standard 1.5 Fcapacitor in parallel with one or more batteries to supply energy to alaser. However, due to the amount of energy typically required bysemiconductor lasers (such as QCLs) per pulse, standard low-capacitycapacitors are not suited for such applications.

In other known battery-powered laser drive circuits, a standard 1.5 Fcapacitor may be disposed in series between a converter and the laser.However, since such capacitors are typically rated for approximately 2.7volts and the typical semiconductor laser requires at leastapproximately 12 volts for operation, such capacitors are not capable ofproviding the proper operating voltage to the laser. Although somecircuits may employ several such capacitors in series, between theconverter and the laser, to store sufficient energy for pulsing and/orotherwise operating the laser, such circuit configurations are plaguedby unacceptable startup delays associated with charging the multiplecapacitors. Moreover, the known drive circuits described above lackefficiency during use since the amount of energy drawn from suchstandard 1.5 F capacitors (approximately 1.25 Joules per pulse fortypical semiconductor lasers) is small relative to the amount of energystored in the capacitor when fully charged (approximately 18 joulestotal).

The exemplary drive circuits 21 described herein, on the other hand,overcome the deficiencies of known semiconductor laser drive circuitsand facilitate supplying tens of watts of peak power to such laserswhile making efficient use of the limited energy stored in the portablepower source 38. Such drive circuits 21 are well suited for the handheldand/or otherwise portable target marking systems 10, 100 of the presentdisclosure, and such drive circuits may be tuned to operate the one ormore light sources 16, 18 to emit a beam 24 having a pulse width in therange of approximately 25 ms to approximately 100 ms, an average powerbetween approximately 2 Watts and approximately 3 Watts, a peak power ofat least 25 Watts, and a pulse rate between approximately 1 Hz andapproximately 3 Hz.

The invention has been described in detail with particular reference toa presently preferred embodiment, but it will be understood thatvariations and modifications can be effected within the spirit and scopeof the invention. The presently disclosed embodiments are thereforeconsidered in all respects to be illustrative and not restrictive. Thescope of the invention is indicated by the appended claims, and allchanges that come within the meaning and range of equivalents thereofare intended to be embraced therein.

1. A target marking system, comprising: a light source configured toemit a beam of radiation; a controller connected to the light source andconfigured to pulse the beam emitted by the light source, the controllerincluding a drive circuit comprising a first converter connected inseries with a second converter, and a capacitor connected in seriesbetween the first and second converters; and a power source connected tothe light source via the drive circuit.
 2. The target marking system ofclaim 1, wherein at least one of the first and second converterscomprises one of a buck converter, a boost converter, a SIPEX converter,a flyback converter, and an inverting converter.
 3. The target markingsystem of claim 1, wherein the first converter is configured to maintaina voltage of the capacitor between approximately 2 volts andapproximately 8 volts while the light source emits the beam.
 4. Thetarget marking system of claim 1, wherein the beam comprises a beam ofthermal radiation.
 5. The target marking system 1, wherein, while thelight source emits the beam, the first converter is configured to draw asubstantially constant current from the power source and to direct thesubstantially constant current to the capacitor.
 6. The target markingsystem of claim 1, wherein the second converter is configured to converta stored voltage of the capacitor to a desired voltage for driving thelight source.
 7. The target marking system of claim 6, wherein the lightsource comprises a quantum cascade laser, and the desired voltagecomprises between approximately 12 volts and approximately 14 volts. 8.The target marking system of claim 1, wherein selectively enabling thesecond converter pulses the beam emitted by the light source.
 9. Thetarget marking system of claim 1, further comprising a switch connectedin series between the light source and the second converter, whereinselectively opening the switch pulses the beam emitted by the lightsource.
 10. The target marking system of claim 1, wherein the capacitorhas a capacity of at least approximately 5 volts.
 11. The target markingsystem of claim 1, wherein the second converter is controlled inresponse to an output power of the beam emitted by the light source, thesecond converter maintaining the output power substantially constant.12. A target marking system, comprising: a light source configured toemit a beam of thermal radiation; an optics assembly receiving the beamand directing the beam to exit a housing of the target marking system; acontroller disposed within the housing and connected to the lightsource, the controller including a drive circuit comprising a firstconverter connected in series with a second converter, and a capacitorconnected in series between the first and second converters; and a powersource connected to the light source via the drive circuit, wherein thedrive circuit provides a substantially constant current to the lightsource during pulsed operation of the light source.
 13. The targetmarking system of claim 12, wherein the housing comprises a mechanismconfigured to mate with a rail of a handheld firearm for mounting thehousing to the rail.
 14. The target marking system of claim 12, whereinselectively enabling the second converter pulses the beam emitted by thelight source.
 15. The target marking system of claim 12, wherein thefirst converter comprises one of a boost converter and a buck converter,the first converter configured to draw the substantially constantcurrent from the power source.
 16. The target marking system of claim12, wherein the first converter is configured to maintain asubstantially constant voltage across the capacitor while the lightsource emits the beam.
 17. A method of controlling a target markingsystem, comprising: directing a substantially constant current from apower source of the target marking system to a light source of thesystem via a drive circuit, the drive circuit comprising a firstconverter connected in series with a second converter, and a capacitorconnected in series between the first and second converters; andgenerating a pulsed beam of radiation with the light source in responseto receipt of the substantially constant current.
 18. The method ofclaim 17, further comprising maintaining an output power of each pulseof the pulsed beam substantially constant.
 19. The method of claim 18,further comprising controlling operation of the second converter inresponse to the output power of each pulse of the pulsed beam.
 20. Themethod of claim 17, further comprising maintaining a voltage of thecapacitor between approximately 2 volts and approximately 8 volts withthe first converter while the light source emits the beam.